The present invention relates to movement transmission cables and, more particularly, to a precision longitudinal movement transmission cable which is particularly applicable as a connecting member between the control lever and the automatic transmission of motor vehicles.
It is well known that in motor vehicles fitted with an automatic transmission as original equipment the connection between the gear lever mounted in the vehicle interior and the automatic transmission is effected by longitudinal movement transmission cable, unlike vehicles provided with a manual transmission as original equipment in which the connection between the gear lever and the transmission is effected generally by a set of articulated rigid metal rods.
The purpose of the longitudinal movement transmission cables is to transfer to the automatic transmission the movement that the driver applies to the gear lever. The flexible nature of these transmission cables is important for their use as a connecting member between the gear lever and automatic transmission in view of the relative positions of both, generally involving an undulating path for the connection.
Generally speaking, these longitudinal movement transmission cables are basically formed by a longitudinal central band or core housed in a casing adapted to the operational conditions of the cable. The central core may slide relative to the casing with the aid of bearings.
Among the known longitudinal movement transmission cables incorporating the novel features characterizing them which have been described in essence in the foregoing paragraphs, the following may be cited: French patent 70.39958, describing a longitudinal movement transmission cable wherein the central core consists of a continuous prismatic band longitudinally movable between two opposed rows of running members which respectively bear against a guide channel attached to the cable casing; French patent 73.15135, describes a longitudinal movement transmission cable comprising a longitudinally movable central prismatic core, two of the sides whereof bear on continuous bands provided with running members which bear against the inner surface of the cable casing; and Spanish patent 308,365, which describes a longitudinal movement transmission cable having a cylindrical central core longitudinally movable on running members housed in a plurality of interconnected supports concentric to the main core.
Generally speaking, the known embodiments of longitudinal movement transmission cables suffer from the fact that they comprise a large number of components parts are complex to make and assemble. This is their main drawback. On the one hand, all of this makes production and assembly costs comparatively more expensive and, on the other hand, causes comparatively frequent breakdowns and/or faulty operation of the cable.